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�Trepani�er Engin�ring <br />Pro%ssional Civil Engineering <br />, ,`,, <br />. i r <br />� (. � <br />'� ' 1 ,� GI <br />DRAINAGE CALCU7�ATION3 ,� rn; �� rn` r / <br />203 DORN AVENtTE i <br />, !C <br />The proposed project involves the construction of a small <br />apartment building at the rear of an existinq lot. The <br />site is flat with a gradient generally northeasterly tc� � <br />southwesterly. <br />Existing on the site is an existinq residence, carport, <br />driveway and other impervious surfaces. <br />The proposal will result in less than 5,000 s.f, of new <br />pavement and, therefore, is exempt from the water quality <br />fe:atures of the Everett Stormwater Ordinance. <br />Retention/Detention will be provided for the increase in <br />impervious area. <br />[�nT•CULATION3 <br />Parvious/Impervious <br />A. Existing <br />Lawn 13,991 @ CN 86 <br />Buildings 2,592 ) <br />Asphalt 921 ) 3,513 S.F. @ CN 98 <br />17,004 S.F, <br />B. Proposed <br />Building 4,B56 ) <br />Asphalt 5,292 ) 10,198 @ CN 9B <br />Grass 6,856 @ CN 86 <br />17,004 S.F. <br />exr�n�s E!/2/00 <br />Time of Concentration <br />Impervious - 5 Minutes By Inspection <br />Pervious - Existinq and Proposed Pervious Takes Same <br />Amount of Time <br />170' @ 1.OB, Grass <br />Retention/Detention Volumes <br />Printouts follow for a 10' X 10' pond with 3�" sideslopes. <br />1420 Hewitt • Everett, Washington 98207 • Everett (425) 259-5556 • FAX (425) 259•5559 <br />